Converting a 110v amp to a 220v amp - Just a transformer, or is there more to it?

[Ted]

Any electronics geeks here?

Is there anything more to converting an amp from 110v to 220v other than having a pro switch to a different transformer?

I'm in Madagascar, and I have a couple of amps that were made for the American market – so they run on 110v – and this country uses 220v.

I always have to use a step-down transformer, and there is always the risk that someone might plug it directly into the wall and blow it – which happened to one of the amps.

Do any other components need to be changed? I'm no electronics tech, but I don't understand why it would need anything but the right transformer. Seems like the transformer transforms the AC to the appropriate DC voltage, and everything downstream from that should be fine.

[64Guitars]

Do any other components need to be changed? I'm no electronics tech, but I don't understand why it would need anything but the right transformer. Seems like the transformer transforms the AC to the appropriate DC voltage, and everything downstream from that should be fine.

I'm no electronics tech either but I know that transformers don't convert from AC to DC. That's the job of the rectifier/filter circuit. The transformer merely changes the voltage. The output from the transformer is still AC.

The power switch and fuse are on the supply side of the transformer, so they may need to be changed. Certainly the fuse rating will change. The power switch and fuse holder might be okay but I wouldn't count on it. Some amps also have the neon power indicator lamp on the supply side and that would need to be changed to a 220 volt lamp. And some amps have a capacitor on the supply side. I'm not sure what its purpose is but I think it might be a safety feature. Anyway, it would need to be changed to a different value.

As for the output side of the transformer, I don't know enough to say for certain but I suspect that, although the AC voltage there might be the same, other properties such as the impedance of the transformer's windings might be different, resulting in a different amount of current. If that's the case, then the rectifier/filter circuit may need to be redesigned to allow for the changed current.

Also, the power frequency in Madagascar is 50 Hz versus the US frequency of 60 Hz. So that might also affect the rectifier/filter circuit.

And sourcing a suitable replacement transformer might be more difficult than you'd imagine. It's not always as simple as finding a 220 volt transformer with the right output voltage. Some guitar amp transformers have multiple outputs at different voltages for different purposes within the amp.

I definitely wouldn't attempt such a modification myself. I'd take the amp to a qualified guitar amp repairman who can properly assess what needs to be done. Also, I'd make sure that they add a power selector switch to allow you to easily switch back to 120 volts if you ever return to the USA.

On the other hand, it might be more practical to treat yourself to a new guitar amp that's designed for 220 volts.

[Ted]

On the other hand, it might be more practical to treat yourself to a new guitar amp that's designed for 220 volts.

Yeah. I don't actually own the blown amp. But it was blown while in my care (by my brother-in-law who was desperately looking for a way to add karaoke to a birthday party). So I'm responsible. It's not that special of an amp. It will never leave Madagascar, according to my friend who owns it.

The technician who will do the work is supposedly very good. We are trying to decide between converting to 220v, or repairing the existing transformer which means the amp will always need a step-down inverter – and inevitably someone will blow it again.

The conversion may cost more than the amp is worth – which is what you suggested. I doubt it. Labor is cheap in Madagascar – even highly-skilled amp technicians.

Thanks for all the info.

[64Guitars]

It's not that special of an amp.

This might be of some use. It's a schematic for the Peavey Basic 50. I couldn't find one for the Basic 60 but if the power section is the same as the Basic 50, then this should help locate the parts as it shows the part numbers for both the 120 volt and 220 volt versions.

https://el34world.com/charts/Schematics/files/Peavey/Peavey_basic50.pdf

The transformer in the 120 volt version is part # 70518712. The 220 volt transformer is part # 70516741. The 120 volt version has a 2 amp fuse. This needs to be replaced with a 1 amp fuse in the 220 volt version. There's an additional component which I believe is a thermal overload switch. It has the same part number (70900110 ) in both versions, so I assume it can be reused. The two capacitors in the 120 volt version aren't used in the 220 volt version.

[64Guitars]

I always have to use a step-down transformer, and there is always the risk that someone might plug it directly into the wall and blow it – which happened to one of the amps.

Out of curiosity, how is it possible to plug an American-style power plug directly into a Madagascar electrical outlet? Based on the pictures on the following pages, it should be impossible.

http://www.electricaloutlet.info/madagascar.html

http://www.electricaloutlet.info/usa1.html

[Flash Harry]

Some transformers are wound for 110/240 volt operation.

It may be there's two primaries which can be connected either in series for 240v operation or parallel for 110v.

Transformers are more efficient at higher frequencies, so American 60hz mains transformers tend to be physically smaller than European ones.

You could get a step down transformer for 240 to 110. These are generally available as step down isolating transformers for power tools.

[Ted]

Out of curiosity, how is it possible to plug an American-style power plug directly into a Madagascar electrical outlet? Based on the pictures on the following pages, it should be impossible.

Type C and E are what come on most things you buy in stores here, but not always. For example, I bought a vacuum cleaner here with a Type G plug. Consequently, just about everyone has a supply of these little bastards:

Some transformers are wound for 110/240 volt operation.

It may be there's two primaries which can be connected either in series for 240v operation or parallel for 110v.

Transformers are more efficient at higher frequencies, so American 60hz mains transformers tend to be physically smaller than European ones.

You could get a step down transformer for 240 to 110. These are generally available as step down isolating transformers for power tools.

I have a step-down transformer. But my brother-in-law didn't know to use it, and I wasn't around to ask, What the fuck are you doing?

Funny thing is that the amp specialist I want to use is really busy right now. Madagascar just celebrated its independence day a couple weeks ago, and there were lots of parties, with lots of live music, and lots of blown amps. This gives me confidence that he does good work.

This might be of some use. It's a schematic for the Peavey Basic 50. I couldn't find one for the Basic 60 but if the power section is the same as the Basic 50, then this should help locate the parts as it shows the part numbers for both the 120 volt and 220 volt versions.

https://el34world.com/charts/Schematics/files/Peavey/Peavey_basic50.pdf

The transformer in the 120 volt version is part # 70518712. The 220 volt transformer is part # 70516741. The 120 volt version has a 2 amp fuse. This needs to be replaced with a 1 amp fuse in the 220 volt version. There's an additional component which I believe is a thermal overload switch. It has the same part number (70900110 ) in both versions, so I assume it can be reused. The two capacitors in the 120 volt version aren't used in the 220 volt version.

I'm going to try to get this schematic to the tech. I was intending to look for it tomorrow, and you saved me the trouble. Thanks!

[Ted]

I hope nobody has been losing sleep over this.

I finally found a guy – a Malagasy guy who works miracles for the IT department at the US Embassy. He was able to convert the amp to 220. I don't now what he did, exactly, but he bought a bunch of parts, and now it works again. It's weird having an amp at home.

[bruno]

https://www.amazon.co.uk/Bronson-Transformers-Toroidal-Converter-Transformator/dp/B07BGCRW36/ref=asc_df_B07BGCRW36/?tag=googshopuk-21&linkCode=df0&hvadid=226609857791&hvpos=&hvnetw=g&hvrand=1117256414636962597&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1006946&hvtargid=pla-445826395638&psc=1